Try:
http://www.burgerking.co.uk/CompanyInfo/contact_us.aspx
Your feedback is invaluable. If you have comments to share, issues to raise or you are not completely satisfied with a recent restaurant visit, call us on our Customer Careline 0845-728-7437
or write to:
Customer Careline
BurgerKing Limited
Charter Place
Vine Street
Uxbridge
Middlesex
UB8 1BZ